Flow Front Analysis In Resin Infusion Process

1
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Flow Front Analysis In Resin Infusion Process
I. Crivelli Visconti, M. Durante, A. Langella, U.
Morano
2
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
RIFT Technology
The Resin Infusion under Flexible Tool (RIFT) is
a closed mould technology to manufacture
composite material and particularly large
component.
3
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
RIFT Technology
Axonometric view of the equipment in a RIFT
process
4
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
RIFT Technology
positioning of reinforcement
positioning of peel-ply
posizioning of resin distributor
positioning of flexible tool
positioning of seal
compacting of the reinforcement
impregnating flow
starting of the pump
positioning of injection system
positioning of outlet system
5
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
The impregnating flows in a RIFT process are
three
The first is a longitudinal flow in the
reinforcement.
The others are caused by the resin distributor
a longitudinal flow in the distibutor
a transversal flow from the distributor to the
reinforcement (it is due to different speed of
the resin in the distributor and in the
reinforcement).
6
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
The analytical model presented in this work
founds itself on Darcys law and an electric
analogy, in which the porous medias opposition
to the resin flow is simulated with an electric
resistance.
Darcys Law
Q volumetric flow m3/s K permeability of
the porous media m2 s section of the porous
media m2 ?p fall of the pressure Pa µ
viscosity of the resin Pas L covered
distance m
7
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
?p is compared to a potential difference ( ?V )
Q is compared to a current intensity ( I )
Electrical Analogy
The terms in the parenthesis can be considered an
electric resistance
8
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
In the Darcys law the volumetric flow is
directly proportional to the section that the
flow crosses.
So the transversal flow (from the resin
distributor to the porous media) depends on the
different distance between the resin in the
distributor and the porous media.
If the longitudinal flow in the distributor is
greater than the transversal one, the distance
between the two longitudinal flow fronts
increases, with consequent increase of the
transversal surface and then transversal flow.
Likewise if transversal flow is greater than
longitudinal one the cross surface decreases so
transversal flow decreases too.
9
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
So, it is possible to say
10
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
The two flows impregnating the reinforcement are
It is possible to consider the following
resistance in parallel position
The total electrical resistence and the
volumetric flow, obtained applying the Darcys
formula, are
11
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Analytical Model
In which kd and kl are the longitudinal
permeability of the resin distributor and of the
preform, sd and sl are the longitudinal cross
section of the resin distributor and of the
preform.
Finally it is possible to calculate the
equivalent permeability of the system as
12
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Experimental Tests
Initially tests were conducted to measure the
permeability of the reinforcement layers and of
the resin distributor using the unidirectional
flow method, wherein the permeability value can
be determined Darcys law.
In these tests only layers of distributor and
only layers of reinforcement were placed between
the mould and the polymeric bag.
resin distributor
fibrous reinforcement
impregnating flow
13
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Experimental Tests
Subsequently some laminates were manufactured by
RIFT using 8 layers of reinforcement and only one
layer of resin distributor. During the
experimental tests the flow front position in the
reinforcement layers has been observed and the
filling time has been measured.
14
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Fem Analysis
A FEM program, RTM Worx, has been used in order
to carry out a comparison between the values of
the filling time measured by experimental tests
and FEM results. The FE model has been generated
using a mesh constituted by triangular shell
elements.
It is possible to set the thickness value but in
thickness direction values of the parameter are
constant, so the model is bi-directional.
15
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Fem Analysis
The RTM-Worx program can give the filling time,
the pressure and the velocity vector when the
physic and geometric properties of the laminates
and the viscosity of the resin are known.
Because this FEM program is 2D, it regards
constant the parameters in the thickness.
So it needs to obtain an equivalent permeability
of the system distributor-reinforcement. It could
be calculate with the described formula of
Electrical Analogy, but also with the Rule of
Mixture
This simple formula doesnt consider the
different impregnating flows in the preform.
In the table the values of the equivalent
permeability calculated by role of mixture and by
the Electrical analogy are reported.
16
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Fem Analysis
simulation of the impregnating process
17
Department of Materials and Production
Engineering University of Naples Federico II,
Italy

• Comparison among the values of filling time
  obtained
• by experimental tests
• by the FEM program with the equivalent
  permeability calculated by Electrical Analogy
  and Rule of Mixture.

18
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
Conclusions

• In this work RIFT process is simulated by a fem
  program (RTM-Worx) and the results of fem
  analysis are compared with experimental tests.
• The FE program generates a bidimensional model,
  considering the properties in thickness
  direction constant. In order to apply this FEM to
  simulate the infusion process an equivalent
  longitudinal permeability of the system resin
  distributor-preform must be considered. For this
  an analytical model, based on electrical analogy
  has been developed to calculate the equivalent
  permeability.
• From the comparison with the experimental data
  it is possible to confirm that setting the
  equivalent permeability value the FEM simulation
  is able to determine the filling time of the
  preform in a RIFT process.

19
Department of Materials and Production
Engineering University of Naples Federico II,
Italy
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